@unknownhost99 Could be as Wayne said, a rogue DHCP server or could be a dozen other things. There is no reason to hide internal network IPs. More often than not we see things on the screen that you don’t see. So you might post a full picture and tell us which IPs your DHCP server and which your FOG server has.

By the way, what is serving DHCP in your network? Has your setup ever worked or is it a fresh install? Which version of FOG?

Beside that you can take a look at the files in the TFTP directory on your FOG server to see if they do exist: ls -al /tftpboot

As well see if the TFTP server is running on your FOG server: netstat -antup | grep 69

@unknownhost99 Could be a rogue DHCP server on your network that you don’t know about. Does the thin client boot from network or is it’s OS on it’s disk locally? Generally they boot from network. I guess we need a whole lot more details to help more.